Title:
SIGNAL SWITCHING CIRCUIT
Document Type and Number:
Japanese Patent JP3173934
Kind Code:
B2
Abstract:
PURPOSE: To automatically switch signals when an additional function circuit is connected to an equipment by connecting the additional function circuit equipped with a certain function to the external terminal of the signal switching circuit and providing the external terminal corresponding to the external terminal of the signal switching circuit at the additional function circuit.
CONSTITUTION: A signal switching circuit 1 is installed on the output side of a circuit 2, which is provided with a certain function, installed inside an audio equipment 11. An input terminal 3 of the circuit 1 is connected through a resistor 9 to a non-inverted input 5 of an OP amplifier 4. An output 7 of the amplifier 4 is connected to an output terminal 8 and further connected through a resistor 10 to an inverted input 6. Five external terminals 13 (a-e) for connecting an additional function circuit 12 from the outside are connected to the circuit 1. When the circuit 12 is not connected to the terminals 13, the output of the circuit 2 is inputted to an input 5 of the amplifier 4 and outputted to the terminal 8 as it is. A resistor 15 is connected between terminals a' and c' of the additional function circuit 12, and terminals b' and e' are serially connected. By connecting this circuit 12, the inverted input 6 of the amplifier 4 is connected to the output of the circuit 2, the non-inverted input 5 is grounded, and the output signal of the circuit 2 is outputted from the terminal 8 after its phase is inverted.
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Inventors:
Toshihito Sawai
Application Number:
JP29817193A
Publication Date:
June 04, 2001
Filing Date:
November 29, 1993
Export Citation:
Assignee:
FUJITSU TEN LIMITED
International Classes:
H04R3/04; H03G5/02; H04B3/02; H04B3/36; (IPC1-7): H04B3/02; H04R3/04
Attorney, Agent or Firm:
Shoichi Ui (4 others)
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